Automated mail processing machines and systems are well known and are commonly used to process bulk and large volume mailings. A typical mail processing system entails numerous complex components working harmoniously to quickly and efficiently process numerous mail pieces. Such typical components generally consist of a means for transporting the mail pieces through the system, a means of placing appropriate postage on the individual pieces, a means of measuring the dimensions of the pieces, a means of weighing the mail pieces to ensure postage conformity, a means of sealing typical self-sealable envelopes, as well as other components which aid in the production and handling of mail pieces.
Typically, mail pieces are placed on the transport means, which delivers the mail pieces seriatim to the means of weighing and measuring the mail piece dimensions. After the mail piece weight and dimensions have been calculated, the correct postage can be calculated, or the individual mail piece can be rejected if the weighing and dimension measurements are set to pre-determined levels. The types of systems using such a weighing means can be infinite. However, as just described, this process must proceed extremely rapidly, be reliable and efficient.
In order to achieve the rapidity, reliability, and efficiency criterion, human intervention must be kept to an absolute minimum. As such, the mail processing machine must be able to handle a vast assortment of mail pieces with varying weights and thickness. It is thus essential that the weighing scale component of the system is reliable, by decreasing complexity in moving parts and accessories, as well as increasing the scale's accuracy and efficiency in order to ensure that the correct postage is calculated and attributable to each individual mail piece.
As alluded to above, mail piece weighing systems conduct two alternative functions within a mail processing system. One is simply weight verification by ensuring that each individual mail piece conforms to predetermined criteria. An alternate function is to calculate the weight of the mail piece and thus automatically transfix the appropriate postage to the mail piece based upon the determined weight. As such, typical mail weighing scale systems must stop a mail piece on top of the scale in order to ensure accurate measurements. However, this process is time consuming because it decreases the amount of mail pieces that can be processed by prolonging the verification and calculation process. Furthermore, typical mail weighing scale systems contain a plethora of complex components and gadgetry, thus having a great tendency to break-down and decrease reliable functionality.
U.S. Pat. No. 5,726,393 to Lyga issued on Mar. 10, 1998 discloses a fixed transport assembly for a mail weighing scale. The disclosed mail weighing scale is intended to be used in conjunction with a mail piece processing system, as described above. The Lyga invention uses a single load cell placed beneath a scale platform. Mail pieces are individually fed onto the scale platform via an incorporated drive belt mechanism. The mail piece is thus stopped, in a horizontal position, on the scale platform and held in place with a vertical force. The load cell, taking into account the tare weight of the scale and vertical force, calculates the mail piece weight. However, this invention has many drawbacks. For one, the mail pieces must be manipulated into a horizontal position in order to be fed into the scale assembly. Furthermore, the system must constantly recalibrate itself to ensure that the scale platform and components associated therewith are taken into account with the tare weight of the scale system. If the calibration is not correct, the reliability and accuracy of the weighing scale is detrimentally effected. Lastly, in order to properly calculate the weight of each mail piece, each piece must momentarily stop on the scale while it is weighed. This thus decreases the mail piece output and efficiency of the system. The present invention overcomes these limitations by continuously weighing the mail pieces in a vertical orientation, without the need to stop the pieces, and providing quick and accurate self-calibration techniques.
U.S. Pat. No. 5,014,797 to Dolan et. al. issued on May 14, 1991 discloses a means of weighing individual mail pieces in a mail processing system. However, a major disadvantage to the Dolan et. al. patent is that each individual mail piece must be clamped to the weighing plate during the weighing phase and to promote transport of the mail piece. As such, the Dolan et. al. patent is very inefficient and is a time consuming process. The present invention overcomes this limitation by not requiring the individual clamping of each mail piece, thus providing a more efficient and time effective means of weighing a plurality of mail pieces.
U.S. Pat. No. 4,856,602, to Cordery et. al. issued on Aug. 15, 1989, discloses a weighing scale that calculates the weight of an object by detecting the shift in the period of harmonic oscillations of a flexibly mounted platform. The invention must first measure the harmonic resonance of the flexible platform prior to the introduction of the object to be mailed. The object is then placed on the platform and a new harmonic resonance is measured. The difference in the harmonic oscillations of the flexible platform determines the object's weight. However, a major drawback to such an invention is the inability to accurately measure the weight of small, light objects due to the apparent lack of perceptible resonance shifts. As such, the Cordery et. al. invention is more suited to bulk packaging and larger mail pieces with weight atypical to conventional mail envelopes. The present invention overcomes this limitation by being better suited to accurately weigh smaller mail pieces by not measuring minute harmonic oscillations.
U.S. Pat. No. 4,787,046 to Feinland et. al. issued on Nov. 22, 1988 discloses a manually operated mail processing system. The user places an individual mail piece on a conventional scale, the scale then calculates the weight of the mail piece and thus determines the correct amount of postage. However, the Feinland et. al. invention can not be used on larger scale bulk mailing because each individual mail piece must be manually manipulated. The present invention overcomes this limitation by being specifically adaptable to use within a complex mass mail processing system. Furthermore, the preferred embodiment of the present invention automatically forwards the weight information to the appropriate systems, thus negating the need for manual input and manipulation. Lastly, the present invention does not require that each mail piece be manually placed upon the scale assembly.
U.S. Pat. No. 3,643,798 to Krupotich issued on Feb. 22, 1972 discloses a mail weighing and sorting machine for large packages. The system has the ability to automatically reject packages which weigh more than a pre-determined criterion. However, the Krupotich patent is not suited for typical bulk mail pieces and cannot be incorporated into a mail processing system. The present invention overcomes this limitation by specifically being adaptable for smaller, conventional sized mailings and not bulk mail packages.